There are a number of known monitoring systems for monitoring the performance of an automobile engine exhaust emission control system employing catalytic converters. One such system is described in U.S. Pat. No. 3,723,070, issued Mar. 27, 1973 by J. H. Houdry--entitled "Catalytic Oxidation Apparatus" and assigned to Oxy-Catalyst, Inc., West Chester, Pa. The Houdry system described in this patent employs a rather complicated and expensive gas analyzer along with temperature recorders and otherwise is too complex and expensive to consider installing on each automobile for continuously monitoring the performance of the engine and the emission control system. U.S. Pat. No. 3,882,451, issued May 6, 1975 to Takesh Fujishiro et al for a "Vehicular Catalytic Converter Failure Alarm System" and assigned to Nissan Motor Company Limited, Yokohama, Japan describes a much simpler and less expensive automobile engine emission control system monitor which is much less complex and less expensive than the monitor adopted by Houdry and which employs temperature sensors for measuring both the inlet and outlet exhaust gas temperatures from a catalytic converter of an automobile engine emission control system. The inlet temperature is compared to a first predetermined level temperature in a first comparator circuit to determine whether the inlet temperature to the catalytic converter is excessive. A second comparator is applied with the temperature difference between the inlet and outlet temperature and this too is compared with a preset temperature difference level in a second comparator circuit. The outputs of the two comparator circuits are then supplied through an AND gate to an alarm circuit. There is no way in which this particular monitor system can be employed or interpreted to assist a driver in conserving fuel as with the present UFI. Additionally, the monitor disclosed in U.S. Pat. No. 3,882,451 compares the catalytic converter inlet temperature to an arbitrarily chosen temperature level which is very difficult if not impossible to establish for all catalytic converter systems. This is due to the fact that the catalytic converter system in question may be inadequate with respect to available oxygen for conversion of pollutants in the automobile engine exhaust via the well known CO+HC oxidation by combustion reaction. Additionally, the linearity of the mass or space velocity of the exhaust gas ratio to the active catalytic surface of the catalytic reactor differs from catalytic converter to catalytic converter and finally the active catalytic surface in any particular catalytic converter is continuously being degraded through operation of the system particularly if any amount of leaded gasoline or contaminated unleaded gasoline is employed in operating the engine. For all of these reasons, the monitor system described in U.S. Pat. No. 3,882,451 is believed to be impractical for general utility purposes and furthermore it is more complex and expensive than the UFI made available by the present invention. U.S. Pat. No. 3,838,569 issued Oct. 1, 1974 to Luther Reck for a "Catalytic Converter Overheating Protection" device and assigned to General Motors Corporation describes a device wherein an electrically heated wire with constant current is installed in the exhaust decontamination system of an automobile engine in a manner such that the wire automatically interrupts the heating circuit by opening contacts upon becoming lengthened due to heating. The circuit automatically is re-established after cooling and the cooling times of the heating wire are measured and employed for determining and indicating the prevailing temperatures in the exhaust decontamination system. This arrangement, while perhaps operable, is too complex and subject to failure for wide-spread use in monitoring the efficiency of an automobile engine emission control system. U.S. Pat. No. 3,921,453, issued Nov. 25, 1975 to George E. Platzer, Jr. for a "Thermocouple System Having a PN Junction Compensation" and assigned to Chrysler Corporation, describes a thermocouple system for monitoring catalytic controllers and requires the use of a PN junction installed at the cold junction of the thermocouple system for cold junction compensation. The Platzer system also requires a reference temperature source, a comparator and a switching circuit wherein the desired switching temperature is entered electrically into the circuit for comparison to a compensated temperature signal derived by the thermocouple and PN junction temperature sensing devices. While the Platzer system employs differentially connected chromel/alumel thermocouples for sensing the inlet and outlet temperatures of a heated object being monitored by the thermocouple system, any similarity to the present UFI thereafter ends. The Platzer thermocouple system appears to be a general purpose temperature measuring system employing cold junction compensation and the use of predetermined or preset reference temperature levels. It is not specifically designed for use as an automobile engine emission control system monitor nor is it now clear how it might be modified to function as such a monitor from the disclosure of this patent.